In the manufacture of multi-pin connectors, it has been often found expedient to use, in place of connector pins made with screw machines, connector pins originally constituted of a unitary piece of an elongated strip of electroconductive material which is formed into pin shape by successive operations performed at successive stations along the strip while the piece is still attached thereto. Connector pins so made from strip provide the advantages over connectors made by screw machines of using less material and of having lower manufacturing costs.
In the manufacture of connector pins of strip origin, the piece from which the pin is made is, in order to arrive at the pin shape, rolled or otherwise formed into a longitudinally elongated, partly or wholly tubular member providing at opposite ends thereof (a) a resilient contact section for making contact with another connector and (b) a terminal section for attachment of the pin to a wire lead or leads, the member having also (c) a hollow mid-section between such contact and terminal sections. Because such piece is so formed into the pin, the strip material of which the pin is made does not peripherally extend continuously around its mid-section but, instead, is interrupted by a discontinuity in the form of an unbonded seam extending over the midsection of the member from its terminal section to its contact section.
The presence of that seam creates the problem that, when it is attempted to connect the terminal section of the pin to a wire lead by soldering, the solder tends to wick along the seam into the contact section of the pin so as to either destroy the resiliency of its contact part or to form an inseparable bond with a mating connector or to produce an open circuit. Wicking of solder flux along such seam may also create difficulties. As a result, connector pins made from strip have been mostly used in multi-pin connectors only when the pin is designed for attachment to a lead in a manner other than by soldering as, for example, by "insulation displacement" wherein the terminal section of the pin has sharp tangs which penetrate the insulation covering of the lead so as to thereby make a mechanical and electrical contact with the wire therein. In instances where the pins must be connected to leads by solder, the prevailing practice still is to have such pins made by screw machines so as to thereby avoid having an unbonded seam and the attendant difficulties caused by its presence.